UploadWizard is an extension that allows a user to upload multiple files with a step-by-step JavaScript wizard. See also:Upload Wizard description page on Wikimedia Commons.

Currently it has this little problem:

The message placeholders <mwe-upwiz-undefined> and <api-error-stasherror> sometimes appear in UploadWizard.

This is what it takes to fix this:
1) go through all the places where message keys are constructed and add all
possibly resulting keys as code comments, per [[mw:Localisation#Using messages]];
2) check that they all exist, fix/add them where missing.

See these bug reports for more information:

Bug 54524 - Missing message <mwe-upwiz-undefined>

Bug 54460 - Missing message <api-error-stasherror> in connection with the UploadWizard

Please address this task with two separate patches, one for each bug report.

Please ask any questions in the bug reports. You will have better chances for quicker and better answers from the project maintainers and other community contributors.

Students are required to read Wikimedia's general instructions first. Patches should be submitted to Gerrit and reference the bug report in the commit message. Improvements to an initial patch must be submitted as an amendment  to the initial patch, not as new patches.